Effect of strontia on the densification and mechanical properties of sol–gel alumina

• Published in: Ceramics international Vol. 32; no. 8; pp. 917 - 922
• Main Authors: Vishista, K., Gnanam, F.D.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-01-2006; Elsevier Science
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; C. Hardness; C. Mechanical properties; C. Toughening; C. Toughness; Ceramic industries; Cermets, ceramic and refractory composites; Chemical industry and chemicals; Cross-disciplinary physics: materials science; rheology; D. Al 2O 3; Exact sciences and technology; Materials science; Miscellaneous; Other materials; Physics; Specific materials; Strontia; Technical ceramics; Strontia; D. Al 2O 3; C. Toughness; C. Mechanical properties; C. Toughening; C. Hardness; Densification; Property composition relationship; Mechanical properties; Composition effect; Hardness; Experimental study; Oxide ceramics; Composite material; Fracture toughness; Optical microscopy; Sol gel process; Technical ceramics; Manufacturing; Alumina; Strontium oxide
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2005.06.014

Boehmite sol was prepared by hot water hydrolysis of aluminum
iso-propoxide using nitric acid as the catalyst. Hydrolysis was carried out at 80
°C for 80
min. Calcium nitrate was added and the peptization was complete at 80
°C for 1
h. The sol was precipitated in ammonia, the precipitate was aged for 24
h, dried at 120
°C and calcined at 500
°C for 3
h. The calcined powder was milled at 230
rpm for 6
h. The amount of calcium oxide was varied from 1 to 20
vol.%. The particle size and particle size distribution of the calcined powders were studied. The average particle size was found to increase with calcia content. The powder was compacted into cylindrical pellets using uni-axial press at 180
MPa and sintered at 1600
°C for 6
h. Mechanical properties such as hardness, fracture toughness, diametrical tensile strength and flexural strength for compacts containing various concentrations of strontium oxide was studied. There was a slight decrease in the density with increase in strontia content. Increase in the mechanical properties such as hardness, fracture toughness and diametrical tensile strength was observed with increase in strontia content.